With Image Loop you can easily create fun slideshows with your choice of effects, skins, and backgrounds. Upload images from social networking sites or your personal picture library.
Diigo is the next generation of social bookmarking. In addition to simply bookmarking the page, you can include a snapshot (screenshot to include in the bookmark view),. You can also highlight information on the web page for inclusion in the bookmark (and also to be noted when someone visits the site from your diigo page. Another neat feature is that you can add sticky notes to the page. Again, these will be viewable by people visiting the page from your bookmark page. There are other features. I suggest visiting the page and taking the 'video tour' as you will love what diigo has to offer!
Scratchpads are an easy to use, social networking application that enable communities of researchers to manage, share and publish taxonomic data online. Sites are hosted at the Natural History Museum London, and offered free to any scientist that completes an online registration form. Scratchpad users include societies, journals, scientists, students and amateurs. Any group with an interest in natural history is eligible for a site and you do not have to have an academic affiliation, or any professional qualification. All you need is a little time, some information you would like to share, and a little experience using the web. You don't need to even be a member of a group, although the best sites are usually those developed by a community who make regular contributions.
A plugin (an extra bunch of programs) that can make your blog a social network site. With this plugin you can add multiple blogs, forums, activity streams, etc.to your class blog.